Taking an environmentally sensitive approach to pest management


Michele Warmund
University of Missouri
Plant Science & Technology
(573) 882-9632

Pecans: A Whole Lot of Shakin' Goin' On

Michele Warmund
University of Missouri
(573) 882-9632

November 7,2023

minute read

Pecan trees are shaking and shimmying as growers harvest pecans in Missouri. During harvest, padded clamps of mechanical shakers are placed around the trunk of pecan trees and generate a vigorous vibrating force that causes the pecans to drop from the tree. Nuts are then swept and vacuumed up by the same machine or a specialized attachment (Figure 1). For harvesting a few trees, nuts are collected from the ground immediately after they fall to prevent loss from wildlife or spoilage. Hand-held tools with a wire basket attached to a long handle are rolled underneath trees to gather nuts.

tall orange machine spewing out pecans into a trailer with wood sides

Figure 1 A sweeper emptying pecans into a trailer for transport to a sorting and drying facility.

After harvest, nuts are sorted from debris and allowed to dry for about two to three weeks to a kernel moisture of about 4%. In-shell pecans can be mechanically dried on a large scale. For small-scale drying, nuts can be placed in a place protected from squirrels and hung in heavy-duty open-weave mesh bags or spread out on wire racks. After drying, in-shell pecans can be refrigerated for up to four months. For long-term storage, in-shell, cracked, or shelled pecans are frozen. Cool temperatures delay kernel shriveling, development of off-flavors and rancidity.

Native pecan trees are usually found in well-drained, fertile soils along rivers and streams and in deep upland soils in the river hills of Missouri. However, improved pecan cultivars are typically grown due to their larger kernel size. Recommended cultivars for Missouri are northern types, which are adapted to a shorter growing season and lower winter temperatures than the southern, paper shell types. Despite their relatively small nut size (100 to 180 nuts per pound), the northern pecan kernels are sweet and flavorful. Other Important factors in cultivar selection are the adaptation zone within the state, flowering type, susceptibility to pecan scab disease, nut productivity, and nut maturity date.

ceramic bowl containing 2 differnt nuts separated by a wooden divider

Figure 2 Northern (left) and southern (right) type pecans each with a kernel.

pile of unshelled pecans

Figure 3 Northern pecans before cracking.

Pollen shed from male catkins and female flower receptivity does not coincide within the same pecan tree. Cultivars that have catkins that shed pollen before the female flower parts are receptive are classified as protandrous or type I. Some of the more widely available protandrous cultivars are 'Hark', 'Gardner', 'Liberty', 'Major', 'Pawnee', 'Shepherd', 'Thayer', and 'Yates 68'.

Protogynous or type II cultivars develop female flowers that are receptive before pollen is shed. 'Earlton', 'Kanza', 'Lakota', and 'Oswego' are protogynous cultivars. For adequate cross-pollination, a protandrous cultivar is planted within 250 feet of a protogynous cultivar. Recommended cultivars by region and their nut characteristics can be found online at https://centerforagroforestry.org/wp-content/uploads/2021/07/Growing-Pecans-in-Missouri-7.02.2021.pdf.

Because pecan trees reach 70 to 100 feet tall and 25 to 75 feet wide at maturity, they are most often grown on large acreages. In addition to pecan scab disease, pecan nut casebearer, hickory shuckworm, pecan weevil, fall webworm, and walnut caterpillar can be problematic. Fortunately, there are several commercial pecan orchards located in Missouri, especially in Bates, Vernon, and Chariton counties, where pecans can be purchased and enjoyed fresh or as an ingredient in many tasty dishes and confections.

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REVISED: November 7, 2023